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Agranular Cortex
Agranular cortex is a cytoarchitecturally defined term denoting the type of heterotypic cortex that is distinguished by its relative thickness and lack of granule cells. Examples are Brodmann area 30, the agranular insula, and the precentral gyrus The precentral gyrus is a prominent gyrus on the surface of the posterior frontal lobe of the brain. It is the site of the primary motor cortex that in humans is cytoarchitecturally defined as Brodmann area 4. Structure The precentral gyrus l ..., the site of the primary motor cortex. An area of cortex that is only slightly granulated is termed dysgranular. References Cerebral cortex {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoarchitecture
Cytoarchitecture (Greek '' κύτος''= "cell" + '' ἀρχιτεκτονική''= "architecture"), also known as cytoarchitectonics, is the study of the cellular composition of the central nervous system's tissues under the microscope. Cytoarchitectonics is one of the ways to parse the brain, by obtaining sections of the brain using a microtome and staining them with chemical agents which reveal where different neurons are located. The study of the parcellation of ''nerve fibers'' (primarily axons) into layers forms the subject of myeloarchitectonics ( History of the cerebral cytoarchitecture Defining cerebral cytoarchitecture began with the advent of —the science of slicing a ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotypic Cortex
Heterotypic cortex consists of those areas of the mature neocortex that deviate markedly from the homogeneous six-layered internal structure seen in the third trimester of human gestation. A few neocortical areas, such as Brodmann area 17 and the granular insular cortex, undergo modification to more than six layers; and in a few areas, such as Brodmann area 4 Brodmann area 4 refers to the primary motor cortex of the human brain. It is located in the posterior portion of the frontal lobe. Brodmann area 4 is part of the precentral gyrus. The borders of this area are: the precentral sulcus in front ( ..., the number of layers is reduced. Heterotypic cortex is contrasted to homotypic cortex, which retains the fetal six-layered pattern into adulthood. The number of heterotypic areas is small and the specific areas differ somewhat by species. (English translation available as ) References External links * More information aBrainInfo Cerebral cortex {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granule Cells
A granule is a large particle or grain. It can refer to: * Granule (cell biology), any of several submicroscopic structures, some with explicable origins, others noted only as cell type-specific features of unknown function ** Azurophilic granule, a structure characteristic of the azurophil eukaryotic cell type ** Chromaffin granule, a structure characteristic of the chromophil eukaryotic cell type. * Astrophysics and geology: ** Granule (solar physics), a visible structure in the photosphere of the Sun arising from activity in the Sun's convective zone ** Martian spherules, spherical granules of material found on the surface of the planet Mars ** Granule (geology), a specified particle size of 2–4 millimetres (-1 to -2 on the φ scale) * Granule, in pharmaceutical terms, small particles gathered into a larger, permanent aggregate in which the original particles can still be identified * Granule (Oracle DBMS), a unit of contiguously allocated virtual memory * Granular synthesis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brodmann Area 30
Brodmann area 30, also known as agranular retrolimbic area 30, is a subdivision of the cytoarchitecturally defined retrosplenial region of the cerebral cortex. In the human it is located in the isthmus of cingulate gyrus. Cytoarchitecturally it is bounded internally by the granular retrolimbic area 29, dorsally by the ventral posterior cingulate area 23 and ventrolaterally by the ectorhinal area 36 (Brodmann-1909). See also * Brodmann area A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. History Brodmann areas were originally defined and numbered by th ... 30 Medial surface of cerebral hemisphere {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agranular Insula
Agranular insula is a portion of the cerebral cortex defined on the basis of internal structure in the human, the macaque, the rat, and the mouse. Classified as allocortex (periallocortex), it is in primates distinguished from adjacent neocortex (proisocortex) by absence of the external granular layer (II) and of the internal granular layer (IV). It occupies the anterior part of the insula, the posterior portion of the orbital gyri The inferior or orbital surface of the frontal lobe is concave, and rests on the orbital plate of the frontal bone. It is divided into four orbital gyri by a well-marked H-shaped orbital sulcus. These are named, from their position, the medial, an ... and the medial part of the temporal pole. In rodents it is located on the ventrolateral surface of the cortex rostrally, between the piriform area ventrally and the gustatory area or the visceral area (granular insular cortex) dorsally. See also * Granular insular cortex References External links ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precentral Gyrus
The precentral gyrus is a prominent gyrus on the surface of the posterior frontal lobe of the brain. It is the site of the primary motor cortex that in humans is cytoarchitecturally defined as Brodmann area 4. Structure The precentral gyrus lies in front of the postcentral gyrus - mostly on the lateral (convex) side of each cerebral hemisphere - from which it is separated by the central sulcus. Its anterior border is represented by the precentral sulcus, while inferiorly it borders to the lateral sulcus (Sylvian fissure). Medially, it is contiguous with the paracentral lobule. The internal pyramidal layer (layer V) of the precentral cortex contains giant (70-100 micrometers) pyramidal neurons called Betz cells, which send long axons to the contralateral motor nuclei of the cranial nerves and to the lower motor neurons in the ventral horn of the spinal cord. These axons form the corticospinal tract. The Betz cells along with their long axons are referred to as upper motor n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |